The invention relates to a thermostated block for laboratory thermostats having wells to receive and make large-area contact with segments of liquid sample filled vials and having heat regulating devices making good thermal contact with the block to generate different temperatures at different sites of the block.
Such a thermostated block is known from U.S. Pat. No. 5,525,300. Two heat-regulating devices in thermal contact with the thermostated block at two of its opposite ends heat it at one end and cool it at the other. A thermal flow runs longitudinally between the heat regulating devices through the thermostated block so that a temperature profile is generated in the longitudinal block direction, resulting in different temperatures. A thermostated block generating such a temperature gradient allows ascertaining the optimal temperature, for instance, in the polymerase chain reaction (PCR) for a temperature stage in this process.
Controlling the temperature of the thermostated block solely at its ends, however, has a drawback. When turning the apparatus ON or when the temperature to be set in the thermostated block changes, the thermostating time delays to the desired equilibrium are substantial on account of the two-end thermostating. Furthermore, the temperature at the middle of the thermostated block may deviate from the desired temperature profile due to environmental effects.
An object of the present invention is to provide a thermostated block of the above type which allows achieving the desired temperature profile faster and without problems.